1. Field of the Invention
The present invention relates to a die for manufacturing honeycomb bodies used for extruding honeycomb structural bodies.
2. Description of Related Art
Generally, various kinds of dies for manufacturing honeycomb bodies are known, having; a die main body including batch supply holes which are opened to a backside surface of the die, slit channels which communicate with the batch supply holes open to a foreside surface of the die, and a chamfered conical-like surface or taper worked portion formed by working an outer peripheral portion of the foreside surface of the die in a taper manner; and a control plate arranged at a portion opposed to the taper worked portion.
FIG. 4 is a schematic view showing one embodiment of a known die for manufacturing honeycomb bodies. In the embodiment shown in FIG. 4, a die 51 for manufacturing honeycomb bodies comprises a die main body 52 and a control plate 53. The die main body 52 has a disk-shape and comprises batch supply holes 61 which are opened to its backside surface (lower surface (not shown) in FIG. 4) and slit channels 62 which are opened to its foreside surface (upper surface in FIG. 4). The slit channels 62 have a crisscross shape at the foreside surface of the die main body 52, and the batch supply holes 61 are communicated with alternate intersection points. An outer peripheral portion of the die main body 52 is worked into a taper shape to form a taper worked portion 63. The control plate 53 is connected to the die main body 52 via a spacer 64 in such a manner that one surface 53a is opposed (parallel in FIG. 4) to the taper worked portion 63.
In the die 51 for manufacturing honeycomb bodies having the construction shown in FIG. 4, a ceramic batch for example is supplied from the batch supply holes 61 which are opened to the backside surface of the die 51, and the thus supplied ceramic batch is extruded from the slit channels 62 which are opened to the foreside surface of the die 51, so as to obtain a honeycomb structural body. Then, it is possible to reduce an inward batch stress when an outer wall is formed and to prevent a collapsing of outer cells i.e. a generation of wrinkle portions in the honeycomb structural body by forming the taper worked portion 63 at the outer peripheral portion of the die main body 52 and by arranging the control plate 53 at a portion opposed to the taper worked portion 63. However, if a thin wall honeycomb structural body having a thin rib thickness, which is required recently, is to be formed, an isostatic strength of the honeycomb structural body become smaller correspondingly since the rib thickness is thin. Therefore, at the outer portion of the honeycomb structural body to which a pressure is liable to be applied, ribs are deformed and wrinkle portions are liable to be generated. As a result, the honeycomb structural bodies thus obtained are liable to be inferior goods.